Internal friction of Cu-CuAlO alloys

Polycrystalline internal oxidize copper alloy with CuA10 particles has been studied by isothermal mechanical spectrometry, above room temperature. The frequency range was 10(-4) to 30 Hz and the maximum strain 2X10(-5). Experiments were carried out on a sample after 18% cold-rolling and successive annealings at various temperatures. The internal friction spectra obtained between 290 and 400 K exhibit only a low frequency background superimposed to a non thermally activated maximum. After annealing at 400 K, the background decreases, a relaxation peak appears and its maximum rises progressively as temperature increases. The relaxation parameters, obtained from the frequency shift of the maximum with temperature, leads to E-a=0.9 eV, and tau(0)=6.9X10(-10) s. These values are similar to those described in the literature for a relaxation peak assigned to dislocation motion inside grains. (C) 2000 Elsevier Science S.A. All rights reserved.